CN111828821A

CN111828821A - Gas/oil mist generator

Info

Publication number: CN111828821A
Application number: CN202010303275.8A
Authority: CN
Inventors: D·瓦尔特
Original assignee: Dropsa SpA
Current assignee: Dropsa SpA
Priority date: 2019-04-18
Filing date: 2020-04-17
Publication date: 2020-10-27
Also published as: IT201900006072A1; EP3725414A1; US20200332952A1

Abstract

An air/oil mist generator (1A) comprising an accumulation chamber (2) in which the mist of oil particles in the air accumulates, the accumulation chamber (2) being provided with at least a first oil mist outlet (4), the generator (1A) comprising an atomizer (3, 3A) fed into said accumulation chamber (2), said atomizer (3) being optimized to operate at a first pressure level and being fed by a first line (BA) of pressurized air at the first pressure level, the generator (1A) further comprising a further atomizer (3A) also fed into the accumulation chamber (2) and optimized to operate at a second pressure level higher than the first pressure level, the further atomizer being fed by A Line (AL) of second compressed air at the second pressure level; the first line (BA) is optionally associated with a check valve (807) which prevents back flow from the accumulation chamber (2).

Description

Gas/oil mist generator

Technical Field

The invention relates to an air/oil mist generator. In particular, the present invention relates to a mist generator for use in a lubrication system.

Background

In the field of lubrication, mist generators applying the venturi principle are known. One of these systems is currently marketed by the applicant under the trade name NEBOL.

It comprises a venturi for injecting pressurized air axially thereto. In the throat portion (minimum passage portion) of the venturi, there is a nozzle conceived for sucking oil. In practice, the oil is drawn through the nozzle by the vacuum created by the venturi effect at the smallest passage section.

Alternative mist generating systems are also well known, such as those in which mixing is carried out without using a venturi system, but by means of a so-called vortex system, such as the one described in patent US 4,335,804.

The advantage of vortex systems over venturi systems is that they are more flexible. Indeed, the vortex is effective over a wider range of air pressures and flow rates (and is therefore self-supporting and produces a fog).

In practice, the pressure at which the system is used to generate the mist is derived from the difference between the supply pressure to the atomizer (whether venturi or vortex type) and the pressure in the mist storage chamber.

For example, if the supply pressure (of the passage) is 6 bar and the pressure of the chamber is 4 bar, the mist generation system will operate at a pressure of 2 bar.

The vortex system allows operation over a greater range of pressures and flow rates than the venturi system.

In all cases, the atomizer that generates the mist (whether venturi or vortex type) is fed to an accumulation chamber that is connected by an outlet to one or more user devices.

One problem encountered with known systems is the fact that: these systems are calibrated to operate in a pressure range close to normal line pressure (i.e., 6 bar). In fact, when the user equipment requires a certain air flow, the pressure difference created in the section across the nebulizer will create a vacuum in the accumulation chamber due to the required flow rate, thereby enabling the nebulizer to work.

When the user equipment requires a very low air flow rate, the pressure in the accumulation chamber does not drop sufficiently for the nebulizer to operate efficiently. In fact, the pressure difference in the section across the atomizer is not sufficient to generate enough mist for lubrication.

Disclosure of Invention

It is an object of the present invention to provide an air/oil mist generator which is improved over the known art.

Another object of the invention is to provide a generator capable of supplying a flow of gas/oil mist to user equipment, wherein a very low air flow rate is required in time, and the oil particles are finely dispersed in the air flow in an extremely uniform manner.

Drawings

Further characteristics and advantages of the invention will become apparent in the description of a preferred but not exclusive embodiment of the device, illustrated by way of non-limiting example in the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view of an atomizer as part of a generator according to the present invention;

FIG. 2 is a simplified cross-sectional view taken along line II-II of FIG. 1;

FIG. 3 is a simplified cross-sectional view of a detail of the generator;

FIG. 4 is an exploded view of the detail circled in FIG. 3;

FIG. 5 is an overall perspective view of a generator according to the present invention;

FIG. 6 is a schematic diagram of a lubrication system including the generator of FIG. 5;

FIG. 7 is a cross-sectional view of a variation of the generator according to the invention, having in particular two atomizers, a high-pressure atomizer and a low-pressure atomizer;

FIG. 8 is a plan view of a detail of the high pressure atomizer of FIG. 7;

FIG. 9 is a perspective view of the generator of FIG. 7; and

fig. 10 is a schematic diagram of a supply system for the generator of fig. 7 and 9.

Detailed Description

With reference to the above figures, reference numeral 1 generally indicates an air/oil mist generator.

Reference must first be made to fig. 5, which shows a possible configuration of the generator. It may comprise a first plate 30 and a second plate 31, which first plate 30 and second plate 31 are clamped in a sealed manner (by means of a gasket T) by tie-rods 32 to a hollow cylindrical element 35 (or an element of different cross-section) so as to form the accumulation chamber 2. A gas/oil mist is formed in the accumulation chamber 2, while it can act as an oil tank.

It is conceivable to install a gauge 37 (fig. 6) on the outside of the accumulation chamber 2 to show the oil level present in the accumulation chamber. The gauge may be of the column type, formed by a small transparent tube, which shows the liquid level in the accumulation chamber 2. Advantageously, there may also be an electronic level sensor (envisaged and not shown) connected to the door 33, which level sensor measures the level of oil present in the chamber. The sensor may suitably be connected to a control unit which is topped up to the liquid level via a further door 36 (e.g. equipped with a manual valve) or via other access to the chamber not shown.

A door 36 equipped with a valve (e.g., a manual valve) may also be used to completely evacuate the accumulation chamber 2.

The first plate 30 has a plurality of through holes (possibly threaded for coupling with plugs or quick couplings 4A) defining various gas/oil mist outlets 4. In practice, when the outlet 4 is open, it communicates with the interior of the accumulation chamber 2 and (see fig. 6) delivers, through each of them, a gas/oil mist to the user devices U1, U2 via suitable ducts T1, T2. Advantageously, the conduits T1, T2 may be intercepted by appropriately controlled solenoid valves E1, E2 or manual valves.

According to the invention, the generator comprises at least one atomizer 3 directly fed into said accumulation chamber 2.

In the case shown, the atomizer 3 is a "medium/low pressure" atomizer, clearly visible in fig. 1.

In the wording herein, the term "medium/low pressure" means that it is configured to work in an optimal way with an intake pressure of 4 to 8 bar, preferably between 5 and 6 bar.

It can be seen that the atomizer 3 may comprise a first nozzle 7 supplied with pressurized air, for example via an annular groove 40 supplied through a passage 41, which passage 41 is directly connected to the outlet of the pressure regulator R.

The nozzle 7 may have a first passage 8, which first passage 8 is supplied by pressurized air from the regulator R.

The channels 8 are clearly visible in fig. 2 and each channel is equipped with an outlet 8A on a surface 70 of the first nozzle, which surface 70 at least partially defines a first chamber 9 that is axisymmetric with respect to the axis a.

In particular, the outlet 8A can be envisaged on a "cylindrical" portion of the first nozzle 7, this section being joined with this converging portion, which will be discussed later.

The channel 8 is positioned to generate a rotation about said axis a of the air fed into the first chamber 9 (see the arrow in fig. 1); preferably, the channels are fed tangentially with respect to a surface 70, which surface 70 is circular in cross-section at the outlet 8A.

The channel 8 may have a constant cross-section, as shown, or may converge towards the outlet 8A.

As shown in fig. 1, the surface 70 of the first nozzle has at least one portion that converges towards the outlet orifice 10 (of said nozzle).

Advantageously, the area of the outlet aperture 10 should be greater than the total area of the outlet 8A to allow a "vacuum" to be created in the chamber 9, the function of which will be explained later.

Advantageously, the ratio between the total area of the outlets 8A and the area of the outlet holes 10 may be less than 0.7, preferably comprised between 0.3 and 0.5. This is to create a vacuum region in the chamber 9 which allows the second nozzle 6 to suck lubricant.

In the illustrated construction, the nozzle may be made in one piece and have a shoulder 41, which shoulder 41 abuts a stop 42 on the first plate 30 for assembly.

Downstream of the first nozzle 7 towards the accumulation chamber 2, a divergent channel 11 is envisaged into which the outlet orifice 10 of the first nozzle 7 feeds. Advantageously, the divergent passage may be defined by a passage with a frustoconical portion produced in the first plate 30.

Returning to fig. 1, the known divergent passage 11 may be defined by a wall 120 (of the first plate 30, for example) which wall 120 is spaced apart from the periphery of the outlet hole 11, at least on one surface comprising the outlet portion of said hole 10 (measurement M1 shown in the figure).

It has been found that this distance M1 can improve the size of the particles fed into the accumulation chamber 2, possibly due to the separation of the turbulence created immediately downstream of the holes 10, because the pressure is immediately restored.

The distance M1 significantly affects the mass and size of the particles and it has been found that the minimum distance is at least half the diameter D1 of the outlet, preferably the minimum distance M1 is at least equal to the diameter D1 of the outlet.

The best measurement of M1 is comprised substantially between one and a half times the outlet diameter and 4.5 times the outlet diameter.

The diverging wall 120 then optimizes the size of the discharged oil particles together with the rotation generated by the passage of the first nozzle 7 (and therefore by the air).

Another feature that affects the oil particle size is the roughness of the walls 120 of the diverging passageway 11. The coarser the portion, the better the coalescence of the larger size particles that are effectively removed from the stream.

In fact, it is speculated that when a "peak" on the surface is encountered, the particle breaks further and becomes smaller. At the same time, a part of the larger particles are stopped in the surface grooves and are thus excluded from the flow.

The optimum roughness value of the walls of the diverging channels 11 is preferably 1.2 μm Ra or more.

Preferably, the roughness is obtained by a treatment that produces a helix on the surface, which ideally rotates counter to the direction of rotation of the vortex of air and oil.

The first chamber 9 may further be defined by a flat surface of an intermediate element 44, which intermediate element 44 may be pressed against the nozzle 7 by means of a suitable threaded element 45, for example screwed onto the first plate 30.

Obviously, between the intermediate element and the first plate 30, but also between the first nozzles 7 and the latter, there are various OR rings to confine the pressurized air in the desired position. The seal is clearly visible in fig. 1.

Advantageously, the channel 8 may be defined by the nozzle 7 and by the flat surface against which the nozzle 7 rests.

For the inflow of oil, the atomizer 3 also has a second nozzle 6, which second nozzle 6 feeds into said first chamber 9, as is known.

For example, the second nozzle 6 is inserted axially in a hole in the intermediate element 44 with a suitable OR ring, and has a tip (in which the delivery hole 6A is formed) that protrudes slightly with respect to the aforementioned flat surface (of the intermediate element) facing the chamber 9.

Advantageously, as shown in fig. 1, the second nozzle 6 has a second delivery orifice 6A coaxial with respect to the axis a. Furthermore, the second nozzle 6 is associated with a supply channel CA that can suck the oil present inside the accumulation chamber 2. For example, the supply channel has a passage 500 connected to a small suction duct 51, which suction duct 51 sucks up the oil accumulated near the bottom of the accumulation chamber 2. The supply channel may have a valve 50 for fine adjustment of the flow rate of oil to the second nozzle 6; advantageously, the flow is visually represented on the gauge 34.

It has been found that for optimum atomiser performance it is preferred that the second nozzle 6 outputs at the outlet 8A of the passageway 8, preferably at the centre line of the outlet 8A.

Furthermore, the second nozzle is useful for axial output with respect to the nozzle 7.

According to one aspect of the invention, the outlet aperture 10 of the first nozzle 7 faces a condenser 5, envisaged inside the accumulation chamber 2, preferably located downstream of the divergent channel 11.

The condenser may have dimensions such as to ensure that the indentations I obtained by the extension of the conical wall 120 are completely contained in the condenser.

It should be mentioned that, in the wording herein, the term "condenser" 5 is used to define a plate-like element 5, which plate-like element 5 is located in front of the outlet of the atomizer 3 (advantageously supported by screws and bolts 46 fixed to the first plate 30).

Even if the condenser 5 is cooled by the inflow of air striking it, its role is not to "condense" (in a physical sense) the oil particles striking it.

It acts at best as a sort of shield that promotes coalescence of the larger-sized oil particles that strike the condenser 5 and cannot be carried by air into the space around said condenser in the accumulation chamber 2 due to their large weight.

Other possible configurations of the atomizer 3 will be illustrated later in this specification with particular reference to fig. 7, but may have the same basic dimensions as the previously described configuration. Moreover, this also applies to another atomizer 3A which will be described with reference to fig. 7.

The operation of the present invention will become apparent from the above description and is substantially as follows.

The accumulation chamber 2 is pre-filled with a certain amount of oil to be able to feed a lead (primer)51 long enough to reach the bottom of the chamber.

When the user equipment needs lubrication, the regulator R sends pressurized air to the nozzle 7 (e.g. via the groove 40 and the source 41).

The pressurized air flows through the nozzle channel 8. Upon reaching the chamber 9, the pressurized air, due to the configuration and arrangement of the channel 8, makes a swirling motion about the axis a of the atomizer 3.

Inside the first nozzle 7, the rotating air is conveyed towards the hole 10 by the converging portion 70 of said nozzle, increasing its speed and reducing its pressure.

Further, due to the relationship between the total area of the outlets 8A and the total area of the holes 10, a vacuum is formed inside the chamber 9, the vacuum draws the oil through the second nozzle 6, and the drawn oil is mixed with the air swirled in the chamber 9 to become powder.

Once the air mixed with oil exits through the hole 10, the diverging portion (separated by M1) generates a sudden recovery of air pressure as the vortex forms and at the same time accumulates heavier oil particles on the wall 120 of the diverging portion, which are thus separated from the air/oil flow.

Only the lighter particles remain suspended in the air flowing through the diverging section and these fine particles diffuse within the accumulation chamber 2.

Assuming that the condenser 5 faces the outlet of the atomizer 3, the former collects a part of the heavy oil particles and condenses them thereon, and then falls onto the bottom of the accumulation chamber 2.

The above structure generates within the accumulation chamber 2 a very fine mist of suspended oil particles of diameter less than about 1 μm, which mist is conveyed by the air flowing through the outlet 4.

The position of the outlet 4 on top of the chamber subjects the oil particles to a further choice, only very small and light particles being able to be transported by the compressed air coming out of the outlet 4.

The above system seeks to produce extremely small oil particles which form a very fine mist and which can be conveyed by the compressed air delivered by the generator 1, thus providing excellent lubricity.

Obviously, particles that condense on the diverging wall 120, on the condenser 5 or that, because they are too heavy, cannot reach the outlet 4, settle onto the bottom of the accumulation chamber 2 and mix with the oil already present therein.

Advantageously, the accumulation chamber 2 is associated with a differential pressure regulator 12, the differential pressure regulator 12 feeding compressed air into the accumulation chamber 2 when the difference between the internal pressure in this chamber and the supply pressure exceeds a preset threshold.

This can occur if the demand for lubrication air from the user equipment is particularly high and exceeds the demand that the atomizer can handle directly.

In this case, the differential pressure regulator 12 (fig. 3 and 4) carries the excess pressurized air inside the accumulation chamber 2, thus allowing the supply to the user devices U1, U2.

In the depicted example, the differential pressure regulator 12 may include a valve element 13, the valve element 13 being loaded by a spring 14 to an opening 15 in communication with a pressurized air supply (i.e., regulator R); at the same time, the spring 14 and a portion of the valve element 13 are in communication with the accumulation chamber 2, causing the valve element 13 to release the opening 15 when the pressure in the accumulation chamber 2 drops below a threshold value (set for example at 2 bar) preset according to the load applied by the spring to the valve element 13, allowing air to flow from the pressurized air supply to the accumulation chamber 2.

In order to prevent air from entering the chamber and negatively affecting the mist present therein, the outlet of the differential pressure regulator 12 inside the accumulation chamber 2 has a silencer 16 which "breaks" the supplied air, preventing significant interference with the mist present inside the chamber.

In the above description, a generator 1 is described having a single atomizer 3, this atomizer 3 preferably operating at medium/low pressure (i.e. the pressure through the supply lines common in many industrial parks, said pressure being about 6 bar).

Systems such as those described above are suitable for providing medium range tools for machines such as cutting machines and therefore also require medium lubrication air flow rates, i.e. at 2-8m³Flow rate in the range of/hour.

In operations where lubrication and cooling are performed using tools requiring lower mist flow rates, the above system has been found to be scarcely applicable. More specifically, it has been found that at low flow rates, i.e. below 2m³The ability to produce a fine particle mist is significantly reduced at a flow rate per hour. This is because the back pressure present in the accumulation chamber 2 is too high to keep the swirl system of the atomizer 3 working.

As shown in fig. 7 to 10, the generator 1A is designed to supply a system with user equipment more efficiently at a highly variable air flow rate and also to keep the concentration of oil particles as constant as possible at low flow rates.

In the drawings, the same reference numerals are used as those used for denoting components having functions similar to those already described.

It will be noted in particular from an analysis of fig. 7 that this generator is substantially similar to the one previously described and also has an atomizer 3 whose function is identical to that described.

For example, the size of the atomizer 3 that works for the generation of mist is the previously described size.

However, in this particular configuration, the atomizer has a nozzle 7 which, in addition to defining the chamber 9, also supplements or better defines the diverging passage 11.

As previously mentioned, the characteristics of the chamber 9 and of the divergent channel 11 for the nebuliser 3 are exactly the same as those already described and therefore do not need to be reported again.

The simplification introduced by adding both the chamber 9 and the diverging channel 11 in the same part is evident. In fact, if the handling of the plate 30 necessary for housing the atomiser 3 is in this variant compared to the situation depicted in fig. 1, it is much simpler if compared to that depicted in fig. 1, since the plate only has a through hole with a cylindrical portion which houses and supports (also by means of the shoulder 41 and the step 42) the new nozzle configuration.

It is clear that also in the case shown in fig. 1, i.e. in the case of a single atomizer 3 present in the generator 1, a simplified version of the nozzle 7 (including the diverging passage 11) and of the plate 30 described herein can be used.

Returning now to the description of the generator 1A, the more significant difference compared to the generator described for the single atomizer version is that there is another atomizer 3A, which atomizer 3A is configured to generate mist starting from a higher pressure relative to the atomizer 3.

For example, the further atomizer 3A has the same conceptual function as the atomizer 3, but is configured to operate at a higher pressure level and a lower flow rate.

Thus, an important difference from the atomizer 3 is the area of the holes 10A and the total area of the outlets 8A (of which only one can be present).

That is, the first nozzle 7 may have an outlet orifice 10, the area of which outlet orifice 10 is larger than the area of the further outlet orifice 10A of the further first nozzle 7A.

Furthermore, the first nozzle 7 may have a first channel 8 supplied with pressurized air, said further first nozzle 7A may have a single further first channel (80), or in any case may have a smaller number of further first channels 80 with respect to the number of channels 8 of the first nozzle 7 supplied with pressurized air. .

The further atomiser 3 may be configured to operate at a supply pressure of between 2 and 4 times the line pressure (typically about 6 bar), preferably about 3 times the line pressure.

In practice, the two

atomizers

3, 3A are geometrically similar, but the other atomizer 3A (in particular the nozzle 7') has dimensions that have been optimized to work at lower air flows (generate mist).

This is evident from an analysis of fig. 8, which fig. 8 shows the configuration of the nozzle 7A in the part defining the chamber 9. In practice, this is a top view of a single nozzle 7A.

This has a single passage 80 (or in any case a smaller number of passages 8 with respect to the atomizer 3). Moreover, the passage section of the channel 80 (and therefore the area of the outlet 8A) is smaller than the outlet 8A of the channel 8 of the atomizer 3. This can be clearly seen when analysing fig. 7, where the outlet 8A of the channel 80 of the further atomiser 3A is hardly visible compared to the channel of the first atomiser.

The remaining dimensions of the further atomiser 3A substantially correspond to (or are at least proportional to) the remaining dimensions of the atomiser 3, but have been optimised to operate at higher pressures.

In particular, again according to fig. 7, it is known that the half angle α 1 of the opening of the diverging portion 11 of the atomizer 3 may correspond to the angle α 2 of said other atomizer 3A. The angle α 1 and/or α 2 may be between 10 ° and 35 °, preferably 15 °.

The height H1 of the diverging portion 11 of the atomizer 3 may correspond to the height H2 of said portion of the other atomizer 3A.

The height H1 and/or H2 is preferably 1.5 times the outlet diameter D1, D2. Preferably, the heights H1, H2 are substantially twice the outlet diameter D1 and/or four times the outlet diameter D2.

The above values are particularly important; in practice, these specific measurements and angles are obtained by rather long and complex optimization procedures based on trial and error. The above ranges and sizes are those that optimize the performance of the device.

The air supply to the further atomizer 3A can be obtained via a line AL, on which a pressure booster 800 (see possible supply diagram in fig. 10) can be present, which pressurizes a reservoir 801 of high-pressure air. Instead of a supercharger, it is obvious that a high-pressure compressor may be used.

The booster may be supplied to a suitable air handling unit 803 and a pressure gauge 804 may be envisaged on the supply line.

The further atomiser 3A (high pressure) may have a source of oil provided via the lead 51 described above. Advantageously, the line CA for feeding the further atomizer with oil does not have any fine adjustment system.

To complete the description of the schematic in fig. 10, it is noted that the supply line BA of the atomizer 3 is identical to that described previously, the only other feature being (possibly) a check valve 807 located on the air supply to the medium/low pressure atomizer 3.

The generator 1A in fig. 7-10 operates essentially as follows.

A predetermined amount of oil is supplied in advance, which is deposited at the bottom of the accumulation chamber 2.

Then, the line pressure (e.g. 6 bar) is provided to the atomizer 3 and the higher pressure, e.g. 20 bar, is provided to the further atomizer 3A.

If no air is required by the other user device U1 or U2, the pressure within the accumulation chamber 2 stabilizes at about 20 bar. The check valve 807 prevents passage of air from the accumulation chamber 2 to the supply line BA leading to the atomizer 3.

When the user equipment requires air, the pressure within the accumulation chamber 2 is reduced according to the required air flow rate.

For a standard air flow rate (e.g. when handling a standard sized tool) the internal pressure of the tank is reduced to the same level as the line pressure (i.e. about 5-6 bar).

In this case, both the atomizer 3 and the other atomizer 3A are in operation. However, the flow rate of mist (and air) provided by the further atomizer 3A is lower (or negligible) compared to the flow rate of mist (and air) provided by the atomizer 3 which actually operates within the optimal range of pressure/flow rate and thus with maximum efficiency in mist generation.

In fact, said further atomizer 3A (which is configured to operate at a higher pressure level and a low flow rate with respect to said atomizer) can in any case operate at line pressure (low), but its contribution to the amount of mist is limited and much smaller than the contribution of the atomizer 3 which is also optimized to operate at normal pressure levels.

The further atomiser 3A is configured to generate swirl at a higher pressure level and a lower flow rate relative to the pressure level and flow rate required to generate swirl in the first atomiser.

If the user equipment requires additional air flow rate, the pressure in the chamber may drop below the preset value. This is due to the fact that: the required air flow rate exceeds the maximum air flow rate that can be delivered by the atomiser 3 and the further atomiser 3A, so the pressure in the accumulation chamber 2 is reduced.

Under these conditions, the atomizer 3 is operated at its maximum air flow rate, and the mist produced thereby is in excess of what would be required for an air flow rate simply through the atomizer.

Thus, under these conditions, the intervention of the differential pressure regulator 12 (also present in this configuration) eliminates the additional passage for feeding air directly into the accumulation chamber 2, increasing the air flow rate with respect to the oil mist produced present in the chamber, thus optimizing the oil/air ratio output by the generator 1A; this prevents over-rich lubrication, exactly as described previously with respect to the generator 1.

At the same time, if the required air flow rate is below the standard, and this happens for example when very small tools are used, the pressure in the accumulation chamber 2 will rise above the optimal working area of the atomizer 3 and then gradually produce less and less mist. At the same time, as the pressure increases, the efficiency of the further atomizer 3A increases, since the latter starts to generate a gradually increasing mist flow into its optimal operating range.

When the pressure inside the accumulation chamber 2 exceeds a certain threshold (for example 6.5), the non-return valve 807 (for example set to a pressure difference of 0.5 bar) intervenes, completely shutting off the atomizer 3. The non-return valve also prevents air from leaving the accumulation chamber 2 via the supply line to the atomizer 3.

When the atomizer 3 is out of operation, all the mist required is produced by the further atomizer 3A, which operates in its optimal operating range, i.e. at a rather high pressure level and a very low flow rate.

The gradual reduction of the flow rate of the atomizer 3 and the increase of the efficiency of the further atomizer 3A are the automatic consequence of the required low air flow rate resulting in an increase of the pressure in the accumulation chamber 2.

Thus, the system shown will automatically adapt to the required air flow rate and also maintain an optimum amount of mist for lubrication at low flow rates.

It should be noted that the increase in the lubrication pressure not only contributes to the generation of a very fine mist, but also makes it possible to cool more effectively small tools which receive more air and more oil, thus facilitating the cutting process described above. Higher air pressure also improves the removal of the shavings produced by the process.

According to a variant of the generator 1A, the valve 805 may be of a nature (for example an automatic valve, set according to the pressure of the accumulation chamber 2, or operated by a solenoid) which can shut off the operation of the other atomizer 3A under specific operating conditions.

This is useful because the production cost of the high-pressure air supplied to the further atomizer 3 is very expensive.

Thus, for example, the valve 805 may be configured to automatically open when the difference between the pressure within the accumulation chamber 2 and the pressure supplied to the nebulizer 3 (e.g., 6 bar line pressure) approaches the minimum pressure required to support swirl in the nebulizer 3 (e.g., 2 bar). In fact, a reduction in the pressure difference may indicate either the need for a very low lubrication flow rate (and therefore the need for intervention of the further atomiser), or the need for air lubrication may be interrupted (in which case no high pressure air is wasted, except for the small amount of air required to raise the pressure of the accumulation chamber 2 to the maximum supply pressure).

Obviously, in a simplified embodiment, it is possible to simply envisage a valve (manual or automatic, controlled by the control unit) which activates the nebuliser 3 or the further nebuliser 3A or both, depending on the treatment to be performed.

Various embodiments of the invention are described herein, but other embodiments can be conceived using the same innovative concepts.

For example, the accumulation chamber 2 may have any configuration, and may also be implemented as a pressurized tank having any cross section, configured differently from the above-described configuration.

Furthermore, it is possible to envisage, for example, an oil tank separate from (and suitably pressurized) accumulation chamber 2, for example, having a circulation system that carries the oil accumulated in accumulation chamber 2 into the main tank.

The construction of the nozzle 7 is optimal in terms of its embodiment, since said one or

more channels

8, 80 are formed between the nozzle 7 and the flat surface of the intermediate element 44. However, the one or more channels in the nozzle can also be produced by means of through-holes.

Furthermore, the nozzle 7 described herein is made as a single part, defining a chamber 9 equipped with a converging portion 70. Obviously, in a variant of embodiment, the nozzle 7 can be made in several parts assembled to each other by gaskets.

Claims

1. An air/oil mist generator (1A) comprising: an accumulation chamber (2) inside which the mist of oil particles in the air accumulates, the accumulation chamber (2) being provided with at least a first mist outlet (4), the air/oil mist generator (1A) comprising an atomizer (3, 3A) which opens into the accumulation chamber (2), the atomizer (3) comprising a first nozzle (7) supplied with pressurized air, the atomizer (3) being supplied by a first line (BA) of compressed air at a first pressure, the air/oil mist generator (1A) further comprising a further atomizer (3A) which also flows into the accumulation chamber (2), the further atomizer (3A) comprising a further first nozzle (7A) supplied with pressurized air, the further atomizer being supplied by a second line (AL) of compressed air at a second pressure higher than the first pressure, the first line (BA) is optionally connected to a check valve (807) which prevents reverse flow from the accumulation chamber (2).

2. The gas/oil mist generator (1A) of claim 1, wherein the further atomizer (3A) is optimized and/or configured to generate mist using a higher pressure relative to the pressure required to generate mist by the atomizer (3).

3. The gas/oil mist generator (1A) according to claim 1, wherein the further atomizer (3A) is optimized and/or configured to operate at a lower flow rate relative to the atomizer (3).

4. The gas/oil mist generator (1A) according to claim 1, wherein the first nozzle (7) has an outlet aperture (10) with an area larger than an area of a further outlet aperture (10A) of the further first nozzle (7A).

5. The gas/oil mist generator (1A) according to claim 1, wherein the first nozzle (7) has a first channel (8) supplied with pressurized air, the further first nozzle (7A) having a single further first channel (80) or having a smaller number of further first channels (80) relative to the first channels (8) of the first nozzle (7) supplied with pressurized air.

6. Gas/oil mist generator (1A) according to claim 1, wherein the further atomizer (3A) is fed through a valve (805), the valve (805) being configured to automatically open when the difference between the pressure in the accumulation chamber (2) and the pressure of the first line (BA) approaches a minimum pressure required to support operation of the atomizer (3), and/or wherein the check valve (807) is arranged to shut off the atomizer (3) when the pressure in the accumulation chamber (2) exceeds a predetermined threshold.

7. The gas/oil mist generator (1A) according to claim 1, wherein the atomizer (3) and/or the further atomizer (3A) comprises a first nozzle (7, 7A) supplied with pressurized air, having at least a first channel (8, 80) supplied with pressurized air, each channel (8, 80) being provided with an outlet (8A, 8A') on a surface (70) of the first nozzle, which surface (70) at least partially defines a first chamber (9) axisymmetric with respect to the axis (A), the channels (8, 80) being oriented to generate a rotation around the axis (A) of the air introduced into the first chamber (9), the surface (70) of the first nozzle providing at least one portion converging towards an outlet aperture (10, 10A), the atomizer (3, 3A) further providing a second nozzle (6), the second nozzle is supplied with oil so that the oil is sucked through the second nozzle (6) due to the air flow through the first chamber (9).

8. Gas/oil mist generator according to claim 7, wherein the outlet aperture (10) of the first nozzle (7) flows into a diverging channel (11).

9. Gas/oil mist generator according to claim 8, wherein the diverging passage (11) is defined by walls (120), the walls (120) being spaced apart (M2, M1) relative to the periphery of the outlet aperture (11) at least in a plane containing the outlet portion of the aperture.

10. Gas/oil mist generator according to claim 1, wherein the outlet aperture (10) of the atomizer (3) and/or the further atomizer (3A) faces a condenser (5) arranged inside the accumulation chamber (2).

11. Gas/oil mist generator according to claim 1, wherein the outlet of the second nozzle (6) faces the outlet (8A, 8A ') of the channel (8, 80), preferably halfway the outlet (8A, 8A').

12. The gas/oil mist generator according to claim 2, wherein the second nozzle (6) has a supply channel that sucks oil present in liquid form inside the accumulation chamber (2), the supply channel comprising a flow regulator (52).

13. The gas/oil mist generator according to claim 1, wherein the accumulation chamber (2) is associated with a differential pressure regulator (12), the differential pressure regulator (12) being configured to introduce compressed air into the accumulation chamber when a difference between an internal pressure of the accumulation chamber (2) and a nebulizer supply pressure (3) exceeds a predefined threshold.

14. The gas/oil mist generator according to claim 13, wherein the differential pressure regulator (12) comprises a valve element (13), the valve element (13) being loaded by a spring (14) in the direction of an opening (15) communicating with a source of pressurized air, the spring (14) and a portion of the valve element (13) communicating with the accumulation chamber (2) so that the valve element (13) releases the opening (15) to allow air to flow from the source of pressurized air to the accumulation chamber (2) when the pressure in the accumulation chamber (2) drops below a threshold defined by the load of the spring on the valve element (13), and/or the outlet of the differential pressure regulator (12) inside the accumulation chamber (2) comprises a muffler (16).

15. Lubrication system comprising an air/oil mist generator (1, 1A) according to one or more of the preceding claims.